1. Field of the Invention
The present invention relates to surgical treatment of isolated articular chondral defects and, more specifically, methods and apparatus for replacement of articular cartilage in knees having chronic anterior cruciate ligament (ACL) deficiency, or isolated articular defects, using reversible synthetic biogel implants for transplantation of articular cartilage in a joint.
2. Description of the Related Art
Chondral defects, i.e., defective cartilage, of the femoral condyles can vary from superficial blemishes and fissures, to large, full-thickness defects. These lesions may be secondary to ligament damage, or may occur as isolated pathology in cruciate normal knees. Treatment has been difficult and controversial. Thus, in many known methods, other indications in the knee are treated, but the chondral lesions usually are left untreated. This approach leads to lesion enlargement and ultimately an advancing arthritic condition.
Chondral defects of the femoral condyles have become widely recognized indications which comprise approximately five percent of all knees undergoing arthroscopy. As such, chondral defects in the knee can be treated by autograft transplantation of bone cores in the knee, as described in U.S. Pat. No. 5,919,196, the disclosure of which is hereby incorporated by reference. However, autografts require additional surgical intervention, increased pain and infusion, and only provide a maximum of 2 or 3 cores to treat smaller focal defects. Furthermore, the donor core must be taken from a location different from the recipient site, thus preventing a perfect match in curvature of the cartilage surface.
As an alternative to the above-described autograft method of treating focal osteochondral defects, an allograft osteochondral transplantation method is known in which a surgeon is provided with a whole cadaver knee from a tissue bank, along with an instrument set containing the full range of sizers and sized instruments. In this allograft method, the surgeon must determine the size of the graft needed and then harvest the properly sized allografts at the time and location of performing the surgery. This method can present certain drawbacks, however, due to several factors, including the preoperative preparation required for the surgeon to harvest and prepare the donor core, the waste from discarding each cadaver knee after the one operation without realizing the full potential for each knee to yield multiple allograft cores, and the comprehensive instrumentation system which must be sent to and recovered from the operation site. A system for harvesting donor cores from a synthetic body part is disclosed in U.S. provisional application No. 60/403,472, filed Aug. 15, 2002, the disclosure of which is incorporated herein by reference.
Moreover, many times the surgeon will determine the presence of a chondral defect during treatment of another condition, and must schedule another surgery to repair the chondral defect. In such instances or in other situations when the surgeon is able to determine the size of the defect prior to the time of the scheduled surgery to repair the chondral defect, the surgery would be much less time-consuming and less burdensome if the surgeon could obtain an appropriately sized, ready-to-use donor graft, prior to the start of the surgery on the patient.
Accordingly, it would be desirable to provide a method of repairing chondral defects using synthetic cores which are formed to the correct size and prepared for transplantation using corresponding instruments.
Various types of synthetic materials for replacement of chondral tissue are known. Salubria™, an elastic biomaterial, sold by Salumedica of Atlanta, Ga. is a hydrogel composition which is similar to human tissue in its mechanical and physical properties. See U.S. Pat. Nos. 5,981,826; 6,231,605, and published application Ser. No. 2001/0029399, the disclosures of which are incorporated herein by reference.
The Salubria™ organic polymer-based material is highly biocompatible and hydrophilic. The hydrogel contains water in proportions similar to those of human hyaline cartilage tissue. Salubria™ closely matches the compliance of human tissue, and has proven to be exceptionally wear resistant and strong, able to withstand millions of loading cycles, making it highly useful as a synthetic osteochondral implant material. Salubria™ can be molded into anatomic shapes and sterilized, making it highly suitable for orthopedic applications.